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A preliminary search has been made with the result of finding the following pertinent art.
This invention relates to a marking device which is used primarily in a multi-spindle screw machine to mark a rotating work piece which is being formed in the screw machine. When a work piece is finished it is desirable to mark it with identifying printing or other types of markings which may be impressed into the work piece. The marking device which has a rotating marking wheel and marking indicia on its periphery is mounted in the multi-spindle screw machine and is moved by the screw machine between a marking position and a non-marking position on the screw machine. When in the marking position the marking wheel engages the work piece and rotates with the work piece to imprint the markings on the work piece.
In the prior art when the marking device is in position to mark the work piece, starter buttons on the marking wheel engage the work piece and this initiates the rotation of the marking wheel and then the marking indicia engage the work piece and the marking wheel is rotated through the marking operation.
The abrupt rotational start of the marking wheel by the engagement of the starter buttons with the work piece will often cause scratching or improper marking of the work piece and the work piece will have to be scrapped. Also, with the starter buttons it is difficult to adjust and control the depth of the impression of the markings in the work piece and because of adjustment of and wear on the starter buttons the marking wheel needs to be replaced frequently.
This invention relates to a marking device which is employed to imprint an impression or some type of marking on a rotating work piece. The marking device has a rotating marking wheel that, when the device is in proper marking position adjacent the work piece to be marked, the marking wheel is set in rotary motion prior to contact of the marking wheel with the work piece and the indicia on the marking wheel then contacts the work piece. The required marking is thereby imprinting on the work piece.
The principal object of this invention is to provide a marking device of novel and improved construction, whereby, rotation of the marking wheel is initiated within the marking device and the rotation of the marking wheel and the rotation of the work piece are substantially synchronized prior to the engagement of the marking wheel indicia with the work piece.
An additional object of this invention is to provide a marking wheel which is biased in the opposite direction of rotation than the marking wheels of the prior art. More specifically, in the prior art the marking wheel is rotationally biased in the return rotary direction by operation of the contact of the marking wheel with the work piece and thereby a spring is stressed or tensioned and the marking wheel is latched in a biased position until the marking device is moved away from the work piece and the latch on the wheel is released to reverse the rotation of the marking wheel so that it returns to its pre-marking position. In the present invention the return of the marking device moves the rack forward thereby reversing the rotation of the marking wheel and biasing the marking wheel for rotation in readiness for imprinting the next work piece.
A basic or fundamental object of this invention is to provide a rotary die marking unit wherein the rotary marking wheel is set in motion prior to the marking wheel making contact with the work piece and thereby reducing the likelihood of producing a defective mark on the work piece. In accomplishing this object of the invention, in one mode, there is provided a biased rack with a latch to hold it in cocked position. The rack has teeth which engage teeth of a pinion. The pinion and the marking wheel are rotatably connected. When the latch on the rack is released, the rack is driven linearly by the force of the biasing means. The teeth on the rack engage the teeth on the pinion, thereby initiating the rotation of the marking wheel. The work piece to receive the marking is rotating at a particular speed and it is an object of this invention to start the rotation of the marking wheel prior to the contact of the marking wheel with the work piece, so that as the two come into contact for the impression to be made on the work piece, the marking wheel is rotating at substantially the same speed of rotation as the work piece. In this way there is no abrupt rotational start of the marking wheel when it contacts the work piece, as in the prior art.
Therefore, it is an important feature of this invention that the marking wheel requires no starter buttons, since the device has its own mechanism to initiate the rotation of the marking wheel. Thereby, the rotation speed of the marking wheel and the work piece are substantially synchronized at the time the two come into contact with each other when the work piece is marked.
An advantage of this invention is that it provides a marking device whereby the depth of the impression of the print or mark can be controlled by adjusting the forward position of the marking device. This will thereby provide a constant and uniform depth of impression each time a mark is made without any other type of adjustment of the body or marking wheel for a particular job. Since the forward working position of the marking device is the only adjustment necessary for a work piece job run, much time will be saved, because of less down time for adjustments and the marking wheel as well as its indicia will last much longer than in the prior art.
Additionally this device requires no special design of starter buttons on the marking wheel or xe2x80x9cbump camsxe2x80x9d to move the device to its final position for the marking operation, as in the prior art. An early no rise cam is all that is utilized, as is know in the prior art, for positioning the device adjacent the work piece prior to the marking operation and only one early no rise cam is required.